Fig. 1. Pump field and probe field drive the same transition |1〉→|2〉, while the control field drives the transition |3〉→|2〉. δ and δ′ are the detuning from resonance. γ21 and γ23 are the decay rates.

Fig. 2. Calculated probe response versus the probe detuning for γ21=γ22=1, χ=6γ21, and χ′=10γ21. (a) δ′=ω23−ω′=60γ21, (b) δ′=ω23−ω′=−60γ21.

Fig. 3. Explanation for the EIT signal. (a) For the zero group-velocity atoms, the pump field and the probe field have the same frequency. Both of the control-probe fields and the control-pump fields satisfy the EIT condition. (b) For other atoms, the frequencies of the three fields are different.

Fig. 4. Explanation for the EIA signal. (a) For the zero group-velocity atoms, the pump field and the probe field have the same frequency. There is no special process taking place. (b) For the atoms with the velocity 3cδ′/ωp, the pump field and the control field satisfy the EIT condition, and the probe field is absorbed by these atoms.

Fig. 5. Experimental setup for Doppler-induced simultaneous EIT and EIA. M, mirror; BS, 1:9 beam splitter; PD, photo detector.

Fig. 6. Experimental results. (a) F=2→F′=1 and F=2→F′=2 are the saturated absorption signals of the transition 5S1/2,F=2→5P1/2, F′=1 and F′=2, respectively. Co(1,2) is the crossover signal. (b) Simultaneous EIT and EIA signal. The ratio of the detuning of the probe field for the EIA signal to that for the EIT signal is 1:3.